Going 7rum to 28 is not that difficult. I take the expander assemby right out of the die, then I set my 28N fl die up in the press so it just contacts the shoulder on a rum case. The die is threaded quite a ways up from where the lock ring is set for my rifle. Lube a case fairly well and run it up- shoulder should have just touched, pull the case down 1/8". Turn the die down 1/4 turn and run the case all the way in, drop the case 1/8" turn the die down another 1/4 turn run the case up. Repeat until you are at the normal lock ring location.
You do have to monitor the case lube, you want very little on the case neck and almost none on the shoulder. Lube will build on the shoulder and cause dents, if those dents get into the neck section as you are moving the shoulder back it creates more work or a garbage case. Either way neck turning is required on the new casing, moving that much brass will give a thick and inconsistent neck.
I find if I don't do it in 1/4 turn increments I may as well not try as the cases buckle trying to move the shoulder any further in one shot.